As in all RPGs, players assume the role of a character (often in a fantasy world) and take control over many of that character's actions.[1] MMORPGs are distinguished from single-player or small multi-player RPGs by the number of players, and by the game's persistent world, usually hosted by the game's publisher, which continues to exist and evolve while the player is away from the game. This is often referred to as being offline.

MMORPGs are played throughout the world.[2] Worldwide revenues for MMORPGs exceeded half a billion dollars in 2005,[3] and Western revenues exceeded US$1 billion in 2006.[4] In 2008, Western consumer spending on subscription MMOGs grew to $1.4 billion.[5]World of Warcraft, a popular MMORPG, had over 12 million subscribers as of October, 2010.[6]